The synaptonemal complex and meiocyte nuclear membrane mediate chromosome interactions during meiotic prophase which result in synapsis, crossing over, chiasma formation, and normal homologue disjunction. Despite the fundamental roles of these structures in sexual reproduction, there is little knowledge of their mechanisms of action or the cellular controls governing their assembly and disassembly. Proposed biochemical studies of synaptonemal complexes and a constituent of the nuclear membrane, the lamina-pore complex, in primary spermatocytes will provide important insights to the composition, structure, assembly, and disassembly of these which could lead to contraceptive methods based on the selective inhibition of meiosis. Synaptonemal complexes will be isolated from nuclei of pachytene spermatocytes from Xenopus laevis by treatment with Joy detergent, DNase I, and 2 M NaC1 followed by sucrose gradient centrifugation. Proteins of the isolated complexes will be analyzed by two dimensional gel electrophoresis. Synaptonemal complex proteins will then be electrophoretically compared to nuclear proteins of somatic cells, premeiotic cells and postmeiotic cells to determine if some of the synaptonemal complex proteins are common to non-meiocyte nuclei and, therefore, potentially important in general nuclear or chromosome structure. The synthesis of synaptonemal complex proteins will be examined following intratesticular injections of 3H-labelled leucine and in cultures of Xenopus spermatocytes. Stage-specific synthesis of individual proteins will be determined by comparing the time required for label to appear in proteins of pachytene synaptonemal complexes to the kinetics of differentiation in vivo and in vitro. Radiolabelled synaptonemal complex proteins will be detected by fluorography of two dimensional gels of pachytene nuclear matrices containing synaptonemal complexes. Lamina-pore complexes in nuclear matrices of primary spermatocytes will be investigated in relation to their structure and protein constituents and the possibility that this structure participates in meiotic prophase chromosome movements. Electron microscopy and selective iodination of peripheral nuclear proteins will be used to compare the nuclear laminae of different meiotic stages to that in premeiotic and somatic cells.